12. wireless mobile comm. - copy

8/8/2019 12. Wireless Mobile Comm. - Copy

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WIRELESS, MOBILE COMMUNICATION

SUBMITTTED BY,

K.RANGANAYAKULU GUPTHA

E-mail: [email protected]&

B.VASUDEVA RAOE-mail: [email protected] BE-ECE,

MRR INSTITUTE OF TECHNOLOGY &

SCIENCES, UDAYAGIRI,

NELLORE (DT).

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mailto:[email protected]:[email protected]:[email protected]:[email protected]


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ABSTRACT:

Wireless communications is a rapidly growing segment of the communications industry,

with the potential to provide high-speed high-quality information exchange between portable

devices located anywhere in the world. Potential applications enabled by this technology

include multimedia Internet-enabled cell phones, smart homes and appliances, automated

highway systems, video teleconferencing and distance learning, and autonomous sensor

networks, to name just a few. However, supporting these applications using wireless

techniques poses a significant technical challenge.

Mobile just means portable. A laptop is a mobile device, as is a PDA or a cell phone. A

desktop would be a mobile device if you had the inclination to carry it around with you. A

wireless device has some sort of network connectivity. A cell phone is wireless, and a laptop

or PDA would be wireless if they had a wireless modem. Similarly, applications are wireless

when they connect and exchange data with a network. One of the many reasons for

developing a cellular mobile telephone system and developing it in many cities is the

operational limitations of conventional telephone systems.

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WIRELESS, MOBILE COMMUNICATION

1) WIRELESS COMMUNICATION

INTRODUCTION:

Wireless communications are nothing new. Since the earlier days of civilization, various

forms of communication took place without the advantage of physical connectivity. In tribal

jungle environment drums were a primary means of communicating. Smoking signals are

also used as a limited distance form of communication. In the nineteenth century, light

beams were used for short haul communications, particularly in military contexts. Wireless

means transmitting signals over invisible radio waves instead of wires. Garage door openers

and television remote controls were the first wireless devices to become a part of everyday

life. Now the cordless keyboard and mouse, PDAs, and digital and cellular phones are

commonplace. Wireless technologies are used for things as simple as making a phone call or

as complex as space research applications.

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WIRELESS CAN BE DIVIDED INTO THESE CATEGRIES:

Fixed wireless-the operation of wireless devices in fixed locations, such as homes and

offices. An example will be equipment connected to the Internet via specialized modems.

Mobile wireless the use of wireless devices or systems aboard motorized, moving

vehicles; examples the automotive cell phone and personal communications services

Portable wirelessthe operation of autonomous, battery-powered wireless devices or

systems outside the office, home or vehicle; examples handheld cell phones

IR wireless the use of devices that convey data via infrared radiation. Example:

portable wireless devices that normally derive their power from batteries.

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ELECTROMAGNETIC SPECTRAM

RANGE OF FREQUENCIES AND THE ASSCIATED BAND CLASSIFICATION:

FERQUENCY BAND

30GHz Extremely high frequency(EHF)

RADIO BASED SYSTEMS:

As radio-based systems emerged, wireless communication became more readily

available and easier to use. An electric transmitter was used to reproduce sound waves and

modulate human speech onto a base band radio frequency. The radio wave carrying the

transmitted signal could travel greater distances, allowing far more reliability and

minimizing the relay process. In radio transmission, human speech must first be converted to

an electrical signal. This signal is analogous to the composition of the sound-pressure

changes produced by the human voice. Radio systems propagate information in the free-

space communication obviates some of the problems faced by other transmission systems.

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ADVANTAGES:

(1) Span bodies of water, such as lakes or rivers, where a cable facility would require special

treatment to prevent seepage onto the copper conductors.

(2) Overcome transmission obstacles posed by mountains and deep valleys, where cable

costs would be prohibitive to install and difficult to maintain.

(3) Bypass the basic interconnection to the telephone provider or post telephone and

telegraph company.

RADIO PROPAGATION:

In radio propagation when the signal is transmitted through an antenna device, the signal

will travel along the earths curvature. As the signal emanates in all directions, the energyfollows the earths curvature. In some cases, reflected power off the earths surface helps

achieve the desired result. At lower frequencies, the signal follows the curve of the earths

surface in what is typically called a ground wave.

SATELLITE RADIO COMMUNICATION:

In 1960 microwave radio signals were transmitted up into the atmosphere to a repeater

floating in space. Called satellite communication, the system was originally designed to

bounce radio waves off an artificial object that was orbiting the earth. An orbiting satellite

offers several distinct advantages. A Stronger signals can be obtained, and over very long

distance the transmission signal requires only a single repeater.

The satellite can be located in a polar, inclined or equatorial orbit. The orbit may be

either circular elliptical at different heights above the surface of the earth. The system

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provide impractical for commercial use, since several satellites were needed to provide

constant communication and the moving antenna equipment required the constant reaming of

dishes. Therefore, a circular orbit around the equator at a height of 22,300 miles was

selected. A satellite at this height takes 24 hours to orbit the earth, resulting in what looks

like a stationary object. In fact, this is called ageosynchronous orbit.

LIGHT BASED SYSTEM:

Another wireless transmission system that is both reliable and inexpensive has proved to

be less popular than radio-based systems is light based system. Infrared light has long been

used as a transmission medium for short-haul local communications. The primary advantagesof infrared systems are easily transportable, typically can be setup and operating with-in an

hour, and do not require expensive licenses or right-of way permits. For all these pulses, the

main disadvantages are the limited distance and limited bandwidth. In addition, infrared

transmissions are subject to even more fading and absorption than microwave systems.

A pinpoint-beam generator in the infrared (invisible) light spectrum operates at a

frequency range of 1012-1015 and a wavelength of 10-4-10-7 to produce high-speed

communications. What should also be understood is that in this context infrared is carried in

open air-waves. If a different medium, such as very pure glass (fiber) were used, the

spectrum of the light would be in the infrared range. It is the fiber that achieves the high-

speed, reliable transmission, since the impairments of the air are overcome on the glass. The

remote controllers for TV sets, radios, lights and other appliances are use infrared signaling.

But they have all the properties of infrared transmission. They can be used only for short

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distances and are highly directional (point to point), invisible light transmitters.

BENEFITS OF WIRELESS COMMUNICATION:

Wireless dramatically improves the convenience, reliability and timeliness of

communication by allowing people to:

Remain persistently connected with others regardless of anyone's location and without

being plugged into anything

Save time and money by shaving seconds off of regular tasks such as locating people,

scanning items and receiving mission-critical alerts

Conduct daily chores effortlessly via a conveniently pocket-sized PDA

Reap the benefits of a rapid pace of innovation in a fast-growing market full of vendors

scrambling to make people's lives easier

WIRELESS SECURITY:

Security is one of the biggest barriers to any kind of wireless initiativewhether it's

implementing a WLAN in a remote office or rolling out wireless handhelds with applicationcapabilities such as e-mail or CRM data. The mobile security vendors are a force to be

reckoned with in this space. The key for IT executives is to cut through the FUD and

determine the real risks to a wireless initiative and the intended benefits. Then the decision

becomes a simple risk management, cost-benefit equation.

CHALLENGES:

Wireless throughput is generally limited compared to the wired alternatives

Uncertainty as to which technologies will remain viable long-term. Each camp (CDMA

and GSM) has several iterations of high-speed wireless service, with carriers choosing

different versions and implementing them at different times. The situation prevents

customers from counting on universal access to a given service.

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Wireless security is lagging

Dropped connections reflect the inherent limitations of wireless signals easily obstructed

by physical barriers such as tunnels, mountains and buildings, as well as radio noise and the

absence of cellular towers in a given region

Small screens in PDAs and other wireless devices limit how much a user can view at

once

Short battery lifespans mean that users must be conscientious about charging their

batteries

RECENT IMPROVEMENTS:

Wireless LANs have improved in the area of security

Devices now have color screens, more memory and faster processors, which devices such

as BlackBerrys have incorporated into their newest designs

Cellular carriers now support IP packets, meaning data can pass over existing voice

networks

Many vendors, including Microsoft, Oracle and SAP, are building wireless functionality

into new versions of their software; on the hardware side, Intel's Centrino processor now

supplies built-in wireless support

Security is improving as vendors add security features to their wireless devices to

compensate for the security limitations inherent in many legacy protocols. 802.11b showed

upwith security and standards

2) MOBILE CELLULAR COMMUNICATION:

INTRODUCTION:

One of the many reasons for developing a cellular mobile telephone system and

developing it in many cities is the operational limitations of conventional telephone systems.

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LIMITATIONS OF CONVENTIONAL TELEPHONE SYSTEMS:

Limited service capability

Poor service performance

Inefficient spectrum utilization

FREQUENCY ALLOCATON:

The FCCs decision to choose 800 MHz was made because of severe spectrum

limitations at lower frequency bands. Therefore it was hard for the FCC to allocate a

spectrum in the lower portions of the 30-400 MHz and since the services of this band had

become so crowded. On the other hand mobile radio transmission cannot be applied at10

GHz because severe propagation loss, and rain activity make the medium improper for the

mobile communications. The mobile phone system operating at 900 & 1800MHz forGSM

and 800MHz forCDMA.

BLOCK DIAGRAM:

A BASIC CELLULAR SYSTEM:

1) MOBILE UNITS:

A mobile telephone unit contains a control unit, a transceiver, and an antenna system.

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drawing unclear. The hexagonal-shaped cells fit the planned area nicely, with no overlap

between the hexagonal cells. Today these hexagonal-shaped cells have already become a

widely promoted symbol for cellular mobile communication.

HEXAGONAL CELL SITES AND THE REAL SHAPES OF THEIR COVERAGES:

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BASE STATION:

Base stations transmit power levels from a few watts to 100 watts or more, depending on

the size of the region or "cell" that they are designed to service. Base station antennae are

typically about 20-30 cm in width and a meter in length, and a height of from 15 to 50 meters

a. These antennae emit RF beams that are typically very narrow in the vertical direction but

quite broad in the horizontal direction. Because of the narrow vertical spread of the beam, the

RF field intensity at the ground directly below the antenna is low.

RADIATION FROM BASE STATION:

BASE STATIONS OF A CITY:

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1) CIRCLULAR UNCOVERED CELL

SITE2) CIRCULAR OVERLAPPED CELL SITE

3) HAEXAGONAL CELL SITE 4) REAL CELL SITE


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OPERATION OF A CELLULAR SYSTEM:

Mobile unit initialization

Mobile originated call

Network originated call

Call termination

Handoff procedure

MAKING A CALL:

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CONCLUSION:

Wireless communication has entered the mainstream as vendors refine the throughput,

stability, security and affordability of an ever-growing range of supported wireless

applications. In the wireless world, your colleagues' whereabouts become totally transparent

as you remain persistently connected with one another in real-time even if some of your

colleagues are flying cross-country.

IT IS NEVERTHELESS TO SAY THE WORLD IS BECOME AS THE WIRELESS

WORLD.

BIBLIOGRAPHY:

1) William C.Y. Lee, MOBILE CELLULAR TELECOMMUNICATION SYSTEM,

McGraw Hill Book Company, 2002.

2) Behrouaz A. Forouzon, DATA COMMUNICATION AND NETWORKING, Tata

McGraw Hill Company, second edition, 2005.

3) Theodore S.Rappaport, WIRELESS. COMMUNICATION, PEARSON

EDUCATION, 2002

4) Regis J.bates, WIRELESS NETWORKED COMMUNICATIONS, McGraw Hill Book

Company, 1995.

5) http://wikimediafoundation.org/

6) http://en.wikipedia.org/wiki/Wireless

7) http://www.stanford.edu/class/ee359/

8) http://www.rfcafe.com/references/electrical/wireless_comm_specs.htm

9) http://www.cio.com/communications/edit/120701_abc_wireless.html

10) http://www.cio.com/technology/wireless/

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http://wikimediafoundation.org/http://en.wikipedia.org/wiki/Wirelesshttp://www.stanford.edu/class/ee359/http://www.rfcafe.com/references/electrical/wireless_comm_specs.htmhttp://www.cio.com/communications/edit/120701_abc_wireless.htmlhttp://www.cio.com/technology/wireless/http://wikimediafoundation.org/http://en.wikipedia.org/wiki/Wirelesshttp://www.stanford.edu/class/ee359/http://www.rfcafe.com/references/electrical/wireless_comm_specs.htmhttp://www.cio.com/communications/edit/120701_abc_wireless.htmlhttp://www.cio.com/technology/wireless/


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12. wireless mobile comm. - copy

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